Field of the Invention
The present invention relates to the use of succinate dehydrogenase Inhibitors for extending shelf life and storage stability of fruits and vegetables and to a method for extending shelf life of fruits and vegetables by applying a succinate dehydrogenase inhibitor to the crops prior to the harvest of the fruits or vegetables.
Description of Related Art
Fresh fruits and vegetables are extremely perishable commodities. Heretofore many techniques have been employed to protect such food products from oxidative degradation, mold attack and moisture penetration and to preserve the freshness, texture and color of the fresh produce.
One of the earliest means of lengthening the shelf life of fruits and vegetables was refrigeration. However, most fresh produce when stored under reduced temperatures for prolonged periods shows adverse effects on the taste, odor or quality of the product from microbial and mold growth above 1,7° C. In addition, storage temperatures below 1,7° C. often show chill injury to the tissue of the produce. Hence, in many instances refrigeration alone is not effective in achieving the desired shelf life for a particular fruit or vegetable.
Coating fresh fruits and/or vegetables is another of these techniques which has been employed with varying degrees of success. Not only must the coating be effective in prolonging the useful shelf life of the fresh product, but the appearance of the commodity must not be altered from that of its natural state. At a minimum, this natural appearance must not only remain unchanged but should ideally be enhanced especially when the fruit or vegetable will be displayed for sale. The selection of a coating material is further complicated where the fruit or vegetable is to be consumed in its natural state and it is considered essential that there be no need to remove the coating. In that event, the coating material must not only be edible, it must not affect or alter the natural organoleptic characteristics of the fresh fruit or vegetable.
Typical of these prior art coatings are the wax emulsions of U.S. Pat. No. 2,560,820 of Recker and U.S. Pat. No. 2,703,760 of Cunning Coatings of natural materials have been employed including milk whey (U.S. Pat. No. 2,282,801 of Musher), lecithin (U.S. Pat. No. 2,470,281 of Allingham and U.S. Pat. No.3,451,826 of Mulder), gelatin together with polyhydric alcohol (U.S. Pat. No. 3,556,814 of Whitman et al.) and protein (U.S. Pat. No. 4,344,971 of Garbutt). Polymers have also been used extensively, viz., a thermoplastic polymer (U.S. Pat. No. 2,213,557 of Tisdale et al.), vinyl acetate polymer (U.S. Pat. No. 3,410,696 of Rosenfield), a hydrophilic polymer (U.S. Pat. No. 3,669,691 of De Long et al.) and the combination of a water soluble polymer and a hydrophobic material (U.S. Pat. No. 3,997,674 of Ukai et al.). Cellulostic materials have found utility in coating fruits and vegetables including hydrated cellulose (U.S. Pat. No. 1,774,866 of Beadle), a combination of cellulose and wax (U.S. Pat. No. 2,364,614 of Beatty), cellulose ether in combination with a fatty acid ester (U.S. Pat. No. 3,471,303 of Hamdy et al.) or monoglyceride and a fatty acid metal salt (U.S. Pat. No. 3,461,304 of Hamdy et al.), or a sucrose ester of a fatty acid (U.S. Pat. No. 4,338,342 of Tan et al.)
Food preservation has for many years employed such mutually exclusive processes as dehydration and freezing. Both of these operations often include a heat treatment, known as blanching, which is conducted prior to the dehydration or freezing step. Blanching is said to reduce enzyme or bacteria level and to prevent or minimize undesirable changes during storage in the dry or frozen state, such as changes in color, odor or texture or loss of vitamins. Blanching may be conducted with steam (e.g., U.S. Pat. No. 2,373,521 of Wigelsworth), hot water (U.S. Pat. No. 2,515,025 of Vahl et al.), hot oxygen-free gas (U.S. Pat. No. 3,801,715 of Smith et al.) or hot air (U.S. Pat. No. 3,973,047 of Linaberry et al.).
The later published prior art reference EP-A-2036438 discloses the postharvest use of different succinate dehydrogenase inhibitors for improving the shelf life of fruits and vegetables. However, preharvest treatment is not disclosed in the reference.
WO 2004/016088 teaches the preharvest application of fluopyram in order to control Botrytis cinerea in cucumbers.
Blacharski, R.; Legard, D.; Bartz,: “The Effect of Preharvest Fungicide Applications on Control of Postharvest Disease” [Online] 1999, XP002536551 teaches the preharvest application of protective fungicides such as captan and thiram to control postharvest occurrence of Botrytis cinerea in strawberries, thereby extending the shelf life of the fruits.
Therefore, there is a strong need for methods for further improving shelf life of fruits and vegetables which avoid the drawbacks resulting from the prior art methods.